Recently， the news of “Hospital Admissions for Rove Beetle Dermatitis Double” has become a trending topic.
Multiple areas in Jinan have reported attacks from rove beetles， often referred to as “flying sulfuric acid.” This has resulted in numerous citizens experiencing symptoms such as skin blisters and ulcerations after swatting them with bare hands or accidentally touching the insects.
According to the Department of Dermatology at Shandong University Qilu Hospital， the number of patients diagnosed with rove beetle dermatitis has doubled compared to previous periods， prompting a reminder for the public to exercise caution.
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A quick search for “rove beetle” online reveals that it consistently appears in trending topics and related news articles year after year， with similar narratives.
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So， what exactly are rove beetles? Are they as dangerous as they are made out to be? And if one encounters them， how can they be avoided or handled safely?
The Rove Beetle That Can Be ‘Disfiguring’: What Is It?
Rove beetles belong to the family Staphylinidae within the order Coleoptera. Most of them are slender， typically measuring between 5 to 10 millimeters in length.
Their forewings are hardened and short， resembling a cleaved shell， while the hindwings are soft， long， and membranous. These hindwings are usually folded and concealed beneath the forewings – hence the name “rove beetle” (隐翅虫， yīn chì chóng， literally “hidden wing insect”). It is these “hidden” hindwings that enable them to fly.
The family Staphylinidae is the most diverse family in the entire animal kingdom， with over 66，000 known species worldwide. While there are numerous species， only about 20 species within the subfamily Paederinae pose a threat to humans. In China， commonly encountered species are typically two or three， with the most prevalent and widely distributed being Paederus chinensis.
These beetles are found in all regions of China except Tibet， with higher populations in tropical and subtropical zones.
Paederus chinensis can be easily identified by its slender， elongated body with alternating red and black markings， and black head and tail.
This striking coloration serves as an aposematic signal， warning other organisms: “I am toxic， do not disturb me.”
Photo by San Die Ji
If You Encounter a Toxic Rove Beetle， Absolutely Do Not Swat It! If You Accidentally Swat One， Follow These 3 Steps.
The reason toxic rove beetles pose a threat to human health is due to a highly acidic toxin they contain called paederin. Research from the Environmental Entomology Group at Shanghai Normal University in 2024 indicates that paederin is not produced by the rove beetles themselves but by their symbiotic bacteria.
These symbiotic bacteria inhabit the reproductive system of female beetles. The toxins they metabolize are stored partly in venom glands and partly excreted externally， without harming the female beetles themselves. This symbiotic relationship allows the female beetles to enhance their survival and reproductive rates with this “chemical weapon，” creating a “win-win” situation with the bacteria. Therefore， it is currently the female beetles that are capable of harming humans.
However， given their small size， males and females appear largely similar to the untrained eye. For the general public， it is advisable to treat any beetle of this appearance as a potentially toxic female.
Paederin is a contact toxin. When it comes into contact with skin， it can cause rove beetle dermatitis， leading to itching， stinging， and burning sensations. The affected skin may develop linear erythema， blisters， or pustules， and after healing， scabs and scarring can be a concern.
For a very small number of individuals with allergic constitutions， more severe reactions may occur.
Generally， when a toxic rove beetle lands on human skin， it rarely actively releases paederin unless it feels threatened.
It is precisely the action of swatting that causes the problem for most people affected by rove beetles. When people discover a rove beetle on their body and panic， swatting it to kill it releases the paederin onto the skin， triggering dermatitis.
A recent victim reported in the trending news accidentally swatted a rove beetle on their neck. They then failed to wash their hands and subsequently rubbed their eyes with the same hand， leading to symptoms around the eyes and neck， nearly causing “disfigurement.”
So， what is the correct way to handle a toxic rove beetle on your person?
It’s simple: Do not swat it. Gently blow it away or flick it off.
If you accidentally swat a toxic rove beetle onto your skin， follow these three steps:
Step 1: Immediately rinse the affected area with plenty of soapy water to wash away any residual toxin and minimize skin damage. If the beetle was near the eyes， use clean water for rinsing instead of soapy water.
Step 2: After washing， refrain from applying alcohol， iodine， toothpaste， or any other “home remedies.” Also， resist the urge to scratch the affected area to prevent secondary infections.
Step 3: If discomfort persists， seek medical attention promptly. Your doctor can prescribe topical medications， oral antihistamines， or antibiotics as needed.
How to Prevent Rove Beetle Encounters?
There are two main scenarios where you might encounter toxic rove beetles in daily life: outdoors and indoors.
In outdoor environments， toxic rove beetles are often found in grasslands near fields or rivers， or under stones and leaf litter in forests.
During the summer and autumn seasons， when engaging in prolonged outdoor activities， it is advisable to wear long-sleeved shirts， long pants， and enclosed shoes to minimize exposed skin. This not only protects against rove beetles but also against mosquitos and ticks.
Rove beetles are attracted to light. If they enter homes， it is usually due to being drawn to lights at night.
To prevent rove beetles from entering your home， close doors and windows in the evening as they are attracted to light. When sleeping， it’s best to turn off any lights near your bed.
In outdoor settings at night， avoid areas with lights near grasslands， take protective measures， and do not casually walk through grassy areas.
Furthermore， rove beetles prefer humid environments. During hot， humid rainy seasons， their numbers and activity frequency increase.
With the rise in global temperatures and an increase in extreme weather events， the active period for rove beetles is also extending. They emerge earlier in warmer periods and remain active as long as temperatures are high， only disappearing with the onset of cold weather.
Generally， rove beetles begin their activity around April， with their peak activity occurring from June to September. Their numbers decline after October， after which they enter a dormant， overwintering phase.
It is important to note that toxic rove beetles do not actively intend to harm humans. In agricultural settings， they are beneficial predatory insects that feed on other pest insects harmful to crops.
Additionally， paederin has been found to inhibit cell mitosis and block protein and DNA synthesis， showing some potential for cancer treatment.
Therefore， there is no need to view toxic rove beetles as malevolent creatures. Understanding them can lead to better coexistence.
References
[1] Zhu Haiqing. Toxic Rove Beetles and Rove Beetle Dermatitis [J]. Insect Knowledge， 1986， 23(3):135-136， 140.
[2] Liu Changli， Yu Maoyun， Zhao Qun， Huang Lin. Study on the Biological Characteristics of Paederus chinensis and Rove Beetle Dermatitis [J]. China Forest Products Industry， 2004(5):24-26.
[3] Zheng Fuke. Research Progress on Toxic Rove Beetles 2: Toxins and Their Medical Significance [J]. Journal of Sichuan Normal University (Natural Science Edition)， 1989， 10(1):17-23.
[4] Chen Shitan， Ning Yu， Xu Hongsheng， et al. Report of 205 Cases of Rove Beetle Dermatitis [J]. Chinese Journal of Dermatology， 1963， 09(02): 96-99.
[5] Nasir， S.， Akram， W.， Khan， R.R， et al. Paederus beetles: the agent of human dermatitis， J Venom Anim Toxins Incl Trop Dis. 2015， 25;21:5
[6] Unveiling a cost of mutualism involving insect-endosymbiont-microbe interactions; Entomologia Generalis; 2024-08-22.
[7] Literature review of the causes， treatment， and prevention of dermatitis linearis. Published: 2016-04 Issue: 4 Volume: 23 Page: taw032. ISSN: 1195-1982.
